CN107612387B - Single-phase AC-DC conversion circuit with network flow pure sine drive pulse frequency modulation and width modulation - Google Patents
Single-phase AC-DC conversion circuit with network flow pure sine drive pulse frequency modulation and width modulation Download PDFInfo
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Abstract
The invention provides a single-phase AC-DC conversion circuit for modulating frequency and width by a network flow pure sine drive pulse, wherein a power circuit is used for completing power conversion of single-phase AC-DC; the control circuit is used for finishing instantaneous detection and AD conversion of output voltage and power grid voltage, carrying out analog operation, digital operation and logic processing according to a voltage outer loop control principle to obtain a corrected duty ratio and a modulated switching frequency, forming PWM (pulse width modulation) driving pulse, and controlling the switching state of a power switch in the power circuit, so that when the power grid voltage is distorted, input current always keeps a sinusoidal waveform without current inner loop control. The invention realizes single-phase AC-DC conversion that the input current always keeps sine when the voltage of the power grid is distorted, the inductor works in a DCM mode, the inductance is low, the invention has the characteristics of simple control, quick response and prevention of electric energy quality pollution, and is widely applied to the application occasions of vehicle-mounted or vehicle wired or wireless chargers, variable frequency air conditioners and the like.
Description
Technical Field
The invention relates to a single-phase power conversion circuit in the technical field of power electronic conversion, in particular to a single-phase AC-DC conversion circuit for modulating frequency and width of net flow pure sine drive pulse.
Background
In order to solve the problem of electric energy quality pollution caused by distortion of the power grid voltage when the AC-DC converter is in a working state, reduce the harm of harmonic current, and inhibit the interference of the harmonic current so as to enable the harmonic current to meet the relevant standard of the harmonic current, a feedback modulation technology is required. The feedback modulation technique of single-phase AC-DC converters has various control strategies, such as conventional double closed-loop control. The effect of adopting the double closed-loop control strategy to restrain the harmonic current is good, but the control circuit is complex and the modulation mode is complicated. In principle, the double closed-loop control needs to adopt a slow voltage outer loop to stabilize the output direct-current voltage, and needs to adopt a fast current inner loop to obtain the network-side sine wave current and the network-side unit power factor. A voltage error amplifier is generally adopted in a traditional voltage outer loop, the inertia of the voltage error amplifier is large, and the dynamic response speed of double closed loop control is influenced to a certain extent.
After searching the prior art of the single-phase AC-DC converter adopting the feedback control principle, the following representative documents are found:
[1] lee and raney waves "high efficiency BOOST type power factor correction preconditioner", proceedings of electrical engineering of china, V24, No.10, 2004.10: 153-156, the main technical features are as follows: the UC38 3854BN analog controller, the voltage error amplifier as the voltage outer loop controller, and the PI regulator as the current inner loop controller are adopted, so that the system design is complex.
[2] What shiyuan and wei No. (research on directional power control of PWM rectifiers based on virtual flux linkage, university of zhejiang, V38, No.12, 2004.11: 1619-: the three-phase rectifier and the voltage error amplifier are used as a voltage outer loop controller, and the slamming control is adopted, so that the switching frequency is suddenly changed, disturbance and noise are introduced, the reliability of the system is reduced, and even the performance of the system is deteriorated.
In summary, the search of the prior art of the single-phase AC-DC converter finds that the traditional single-phase AC-DC conversion circuit lacks a feedback control strategy and a corresponding power circuit topology which can better cope with the voltage distortion of the power grid, and has the unfavorable phenomenon that harmonic current is injected into the power grid, thereby causing the problem of power quality pollution of the power grid.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a single-phase AC-DC conversion circuit for modulating frequency and width of a network current pure sine drive pulse, realizing single-phase AC-DC conversion that the input current always keeps sine when the voltage of a power grid is distorted, and having the advantages of simple control, quick response and prevention of power quality pollution.
The invention is realized by the following technical scheme.
The invention provides a single-phase AC-DC conversion circuit for modulating frequency and width of net flow pure sine drive pulse, which comprises a power circuit and a control circuit, wherein:
the power circuit is used for completing power conversion of single-phase AC-DC;
the control circuit is used for completing instantaneous detection and AD conversion of the output voltage and the power grid voltage, processing the output voltage and the power grid voltage according to a voltage outer loop control principle (including analog operation, digital operation and logic processing) to obtain a corrected duty ratio and a modulated switching frequency, forming PWM driving pulses, and controlling the PWM switching state of a power switch in the power circuit so that when the power grid voltage is distorted, the input current always keeps a sine waveform; the method specifically comprises the following steps:
the control circuit comprises a power grid voltage detection circuit, a voltage boosting circuit, an output voltage detection circuit and a DSP program unit; wherein:
the power grid voltage detection circuit is used for inputting the voltage obtained by dividing the power grid voltage after passing through the voltage transformer and the voltage division circuit a into the voltage boost circuit as a power grid voltage detection value;
the voltage boosting circuit is used for boosting the voltage detection value of the power grid and sending the voltage detection value to the DSP program unit;
the output voltage detection circuit is used for taking the voltage obtained by dividing the output voltage through the voltage division circuit b as an output voltage sampling value, filtering the output voltage sampling value through the RC filter circuit and sending the filtered output voltage sampling value to the DSP program unit;
and the DSP program unit is used for processing the power grid voltage detection value and the output voltage sampling value to obtain the corrected duty ratio and the modulated switching frequency, so as to form PWM driving pulse and control the PWM switching state of a power switch in the power circuit.
Preferably, the power circuit comprises a filter circuit and a rectifier circuit, wherein:
the filter circuit mainly comprises an LC filter inductor and an LC filter capacitor, wherein one end of the LC filter inductor is connected with a live wire of a power grid, and the other end of the LC filter inductor is connected with a zero line of the power grid after passing through the LC filter capacitor to form the LC filter circuit;
the rectifying circuit comprises a single-phase rectifying bridge, a ninth diode and an electrolytic capacitor; the single-phase rectifier bridge mainly comprises first to eighth diodes, first to third power switches, a first inductor and a second inductor, wherein a first bridge arm of the single-phase rectifier bridge comprises first to fourth diodes, a first power switch and a first inductor, the second diode, the third diode, the first power switch and the first inductor form a loop in the bridge arm, the first diode is positioned at the high end of the first bridge arm, and the fourth diode is positioned at the low end of the first bridge arm; the second bridge arm of the single-phase rectifier bridge comprises fifth to eighth diodes, a second power switch and a second inductor, wherein a sixth diode, a seventh diode, the second power switch and the second inductor form a loop in the bridge arm, the fifth diode is positioned at the high end of the second bridge arm, and the eighth diode is positioned at the low end of the second bridge arm; a third bridge arm of the single-phase rectifier bridge is composed of a third power switch; the high ends of the first bridge arm and the second bridge arm are connected in a common cathode mode and form an output voltage anode after passing through a ninth diode; the low ends of the first bridge arm and the second bridge arm are connected in a common anode mode, and an output voltage cathode is formed; the middle points of the first bridge arm and the second bridge arm are connected with two ends of the LC filter capacitor; an electrolytic capacitor is connected in parallel between the positive electrode and the negative electrode of the output voltage.
Preferably, the control circuit comprises a grid voltage detection circuit, a voltage boost circuit, an output voltage detection circuit and a DSP program unit, wherein:
the input end of the power grid voltage detection circuit is connected with the input end of the power circuit, the output end of the power grid voltage detection circuit is connected with the input end of the voltage boosting circuit, the output end of the voltage boosting circuit is connected with the DSP program unit, the input end of the output voltage detection circuit is connected with the output end of the power circuit, and the output end of the output voltage detection circuit is connected with the DSP program unit.
Preferably, the input end of the power grid voltage detection circuit is connected with the input end of the power circuit, and includes a voltage transformer, a first resistor and a second resistor, the power grid voltage is input into the power grid voltage detection circuit after passing through the voltage transformer, the first resistor and the second resistor are connected in series and then connected in parallel to the secondary side of the voltage transformer, one end of the second resistor is grounded to form a voltage division circuit a, and the voltage divided at the two ends of the second resistor is input into the voltage boost circuit as a power grid voltage detection value.
Preferably, the input end of the voltage boosting circuit is connected to the output end of the power grid voltage detection circuit, and includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, an operational amplifier and a first capacitor, an external power source is input to the positive phase input end of the operational amplifier through the third resistor, one end of the fifth resistor is grounded, the other end of the fifth resistor is connected to the sixth resistor, the sixth resistor is connected in parallel between the negative phase input end and the output end of the operational amplifier, the fifth and sixth resistors divide the voltage of the output end of the operational amplifier, the voltage divided by the fifth resistor is input to the negative phase input end of the operational amplifier, the fourth resistor is connected in series to the output end of the operational amplifier, and then is grounded through the first capacitor, and the power grid voltage detection value is boosted and then sent to the DSP program unit (the first analog-to-digital conversion module).
Preferably, the input end of the output voltage detection circuit is connected to the output end of the power circuit, and includes a seventh resistor, an eighth resistor, a ninth resistor, an RC filter resistor and an RC filter capacitor, the seventh resistor, the eighth resistor and the ninth resistor are connected in series to form a voltage divider circuit b, the voltage divided at the two ends of the ninth resistor is used as an output voltage sampling value, one end of the RC filter resistor is connected to the ninth resistor, the other end of the RC filter resistor is grounded after passing through the RC filter capacitor to form the RC filter circuit, and the output voltage sampling value is filtered and then sent to the DSP program unit (the second analog-to-digital conversion module).
Preferably, the resistance values of the seventh resistor and the eighth resistor are both greater than the resistance value of the ninth resistor.
Preferably, the DSP program unit includes fifteen digital modules, which are respectively: the device comprises a first analog-to-digital conversion module, a second analog-to-digital conversion module, a third analog-to-digital conversion module, a phase-locked loop module, a reference sine wave generation module, a switching frequency waveform generation module, a sawtooth carrier generation module, a duty ratio correction module, a voltage error amplification module, a fundamental wave filtering module, a third harmonic filtering module, a fifth harmonic filtering module, a multiplier module, an amplitude limiting module and a comparison and modulation module, wherein:
the input end of the first analog-to-digital conversion module is connected with the output end of the power grid voltage detection circuit, and the analog quantity of the power grid voltage detection value is converted into digital quantity which is then sent to the phase-locked loop module;
the input end of the phase-locked loop module is connected with the output end of the first analog-to-digital conversion module, the phase of the power grid voltage is fixed, the influence caused by the phase drift of the power grid voltage is eliminated, and then the instantaneous phase of the power grid voltage is sent to the reference sine wave generation module;
the input end of the reference sine wave generation module is connected with the output end of the phase-locked loop module, receives the transmitted power grid voltage phase parameter, generates a reference sine wave for modulating the switching frequency by combining an internally set frequency fixed value parameter, and respectively sends the reference sine wave to the switching frequency waveform generation module and the duty ratio correction module;
the input end of the switching frequency waveform generating module is connected with the output end of the reference sine wave generating module, appropriate waveform transformation is carried out on the basis of the reference sine wave to generate a switching frequency waveform, and the switching frequency waveform is sent to the sawtooth carrier wave generating module;
the input end of the sawtooth carrier generation module is connected with the output end of the switching frequency waveform generation module, and according to the input switching frequency waveform, unit amplitude sawtooth carriers of corresponding periods are generated and sent to the first input end of the comparison modulation module;
the input end of the duty ratio correction module is connected with the output end of the reference sine wave generation module, and the input switching frequency function is subjected to squaring operation to obtain a corresponding duty ratio correction coefficient which is sent to the first input end of the multiplier module;
the input end of the second analog-to-digital conversion module is connected with the output end of the output voltage detection circuit, and the analog quantity of the output voltage sampling value of the power circuit is converted into digital quantity which is then sent to the first input end of the voltage error amplification module;
the input end of the third analog-to-digital conversion module gives a reference voltage, the analog quantity of the reference voltage value is converted into a digital quantity, and the digital quantity is sent to the second input end of the voltage error amplification module;
the first input end of the voltage error amplification module is connected with the output end of the second analog-to-digital conversion module, the second input end of the voltage error amplification module is connected with the output end of the third analog-to-digital conversion module, the difference value of the output voltage detection value and the reference voltage is amplified, and then the amplified output voltage is sent to the fundamental wave filtering module for filtering;
the input end of the fundamental wave filtering module is connected with the output end of the voltage error amplifying module, so that a double fundamental wave component in a voltage error signal is filtered, and then the voltage error signal is sent to the third harmonic wave filtering module for further filtering;
the input end of the third harmonic filtering module is connected with the output end of the fundamental wave filtering module, and is used for filtering out a second harmonic component in the voltage error signal and then sending the voltage error signal to the fifth harmonic filtering module for further filtering;
the input end of the fifth harmonic filtering module is connected with the output end of the third harmonic filtering module, double fifth harmonic components in the voltage error signal are filtered, the filtered voltage difference signal is converted into a corresponding duty ratio, and then the duty ratio is sent to the multiplier module;
the first input end of the multiplier module is connected with the output end of the duty ratio correction module, the second input end of the multiplier module is connected with the output end of the fifth harmonic filtering module, the input duty ratio is multiplied by the duty ratio correction coefficient, certain correction is carried out on the input original duty ratio, and then the corrected duty ratio is sent to the amplitude limiting module;
the input end of the amplitude limiting module is connected with the output end of the multiplier module, amplitude limiting processing is carried out on the corrected duty ratio, the amplitude limiting processing can prevent the condition that the duty ratio is larger than or equal to the unit amplitude caused by system errors or other non-ideal factors, the power circuit is prevented from being damaged, and then the amplitude-limited duty ratio is input into the second input end of the comparison modulation module;
the first input end of the comparison modulation module is connected with the output end of the sawtooth carrier generation module, the second input end of the comparison modulation module is connected with the output end of the amplitude limiting module, the input constant-amplitude variable-frequency sawtooth carrier is compared with the waveform of the instantaneous duty ratio, and PWM driving pulses with modulated periods and duty ratios are generated;
and the output end of the DSP program unit is connected with a gate pole of a power switch in the power circuit.
Compared with the prior art, the invention has the following beneficial effects:
in the power circuit, when three power switches work normally, the PWM (pulse width modulation) switch states are completely the same, and the same PWM driving pulse sent by a voltage outer loop control circuit is shared; the control circuit simultaneously adjusts the PWM duty ratio and the switching frequency according to the instantaneous distortion condition of the power grid voltage so as to obtain the sine wave type current on the power grid side.
The control circuit combining the analog circuit and the DSP program unit is designed, namely voltage outer ring control, the output of the voltage outer ring is closer to pure direct current, fluctuation components do not exist, the traditional double-ring control of combining a current inner ring and a voltage outer ring is not needed, the complexity of the control circuit is favorably reduced, and the control precision of network side current is improved; the power circuit has a novel structure, the three power switches have the same switching state, and the same path of PWM driving pulse output by the control circuit can be shared, so that the control difficulty of the power switches is reduced to a certain extent; the control circuit is accurate and flexible, the power circuit is novel and efficient, and the input current at the network side is always sinusoidal no matter whether the network voltage is distorted or not, so that the electric energy quality is effectively prevented from being polluted in the AC-DC conversion process; by adopting the switching frequency modulation technology, the interference transmitted from the network side is converted from narrow-band distribution to wide-band distribution, thereby being beneficial to dispersing EMI interference energy and improving the EMC level of the whole circuit.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic diagram of a control circuit of the present invention.
Fig. 2 is a schematic diagram of a power circuit of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
As shown in fig. 1 and fig. 2, the present embodiment provides a single-phase AC-DC conversion circuit with modulated width of net flow pure sinusoidal driving pulse frequency, which includes a control circuit and a power circuit, wherein: the control circuit is used for completing instantaneous detection and AD conversion of the output voltage and the power grid voltage, carrying out analog operation, digital operation and logic processing on the output voltage and the power grid voltage according to a voltage outer ring control principle to obtain a corrected duty ratio and a modulated switching frequency, forming PWM (pulse width modulation) driving pulses, and controlling the switching states of three power switches in the power circuit so that the input current always keeps a sine waveform when the power grid voltage is distorted; the power circuit is used for completing power conversion of single-phase AC-DC; the embodiment realizes that the input current always keeps sinusoidal single-phase AC-DC conversion when the voltage of a power grid is distorted, the inductors L2 and L3 work in a DCM mode, the inductance is low, the control is simple, the characteristics of preventing the electric energy quality pollution are realized, and the method is widely applied to the application occasions of vehicle-mounted or vehicle wired or wireless chargers, variable frequency air conditioners and the like.
The single-phase AC-DC conversion circuit that net flow pure sine drive pulse frequency modulation was transferred wide of this embodiment includes power circuit and control circuit, wherein: the control circuit is used for completing instantaneous detection and AD conversion of output voltage and power grid voltage (grid voltage), carrying out analog operation, digital operation and logic processing according to a voltage outer ring control principle to obtain a corrected duty ratio and a modulated switching frequency to form PWM (pulse width modulation) driving pulse and control the switching state of a power switch in the power circuit, so that when the power grid voltage is distorted, input current can always keep a sine waveform; the power circuit is used for completing power conversion of single-phase AC-DC.
The control circuit comprises a power grid voltage detection circuit, a voltage boosting circuit, an output voltage detection circuit and a DSP program unit; wherein:
the power grid voltage detection circuit is used for inputting the voltage obtained by dividing the power grid voltage through the voltage division circuit a into the voltage boosting circuit as a power grid voltage detection value;
the voltage boosting circuit is used for boosting the voltage detection value of the power grid and sending the voltage detection value to the DSP program unit;
the output voltage detection circuit is used for taking the voltage obtained by dividing the output voltage through the voltage division circuit b as an output voltage sampling value, filtering the output voltage sampling value through the RC filter circuit and sending the filtered output voltage sampling value to the DSP program unit;
and the DSP program unit is used for processing the power grid voltage detection value and the output voltage sampling value to obtain the corrected duty ratio and the modulated switching frequency, so as to form PWM driving pulse and control the PWM switching state of a power switch in the power circuit.
The method specifically comprises the following steps:
as shown in fig. 2, the power circuit includes a filter circuit and a rectifier circuit, wherein:
the filter circuit mainly comprises an LC filter inductor L0 and an LC filter capacitor C0, wherein one end of the LC filter inductor L0 is connected with a live wire of a power grid, and the other end of the LC filter inductor L0 is connected with a zero wire of the power grid after passing through the LC filter capacitor C0 to form the LC filter circuit;
the rectifying circuit comprises a single-phase rectifying bridge, a ninth diode and an electrolytic capacitor; the single-phase rectifier bridge mainly comprises first to eighth diodes, first to third power switches, first and second inductors, wherein a first bridge arm of the single-phase rectifier bridge comprises the first to fourth diodes, the first power switch and the first inductor, a loop is formed in the bridge arm by the second diode D2, the third diode D3, the first power switch S1 and the first inductor L1, the first diode D1 is located at the high end of the first bridge arm, and the fourth diode D4 is located at the low end of the first bridge arm; the second bridge arm of the single-phase rectifier bridge comprises fifth to eighth diodes, a second power switch and a second inductor, wherein a sixth diode D6, a seventh diode D7, a second power switch S2 and a second inductor L2 form a loop in the bridge arm, the fifth diode D5 is located at the high end of the second bridge arm, and the eighth diode D8 is located at the low end of the second bridge arm; the third bridge arm of the single-phase rectifier bridge is composed of a third power switch S3; the high ends of the first bridge arm and the second bridge arm are connected in a common cathode mode and form an output voltage anode after passing through a ninth diode D9; the low ends of the first bridge arm and the second bridge arm are connected in a common anode mode, and an output voltage cathode is formed; the middle points of the first bridge arm and the second bridge arm are connected with two ends of the LC filter capacitor C0; an electrolytic capacitor E1 is connected in parallel between the positive electrode and the negative electrode (two ends of the positive electrode and the negative electrode) of the output voltage.
As shown in fig. 1, the grid voltage detection circuit, the voltage boost circuit, the output voltage detection circuit and the DSP program unit of the control circuit are provided, wherein:
the input end of the power grid voltage detection circuit is connected with the input end of the power circuit, the output end of the power grid voltage detection circuit is connected with the input end of the voltage boosting circuit, the output end of the voltage boosting circuit is connected with the DSP program unit, the input end of the output voltage detection circuit is connected with the output end of the power circuit, and the output end of the output voltage detection circuit is connected with the DSP program unit.
Furthermore, the input end of the grid voltage detection circuit is connected with the input end of the power circuit, and comprises a voltage transformer TR1, a first resistor R1 and a second resistor R2, the grid voltage passes through the voltage transformer TR1 and then is input into the grid voltage detection circuit, the first resistor R1 and the second resistor R2 are connected in series and then are connected in parallel to the secondary side of the voltage transformer TR1, one end of the second resistor R2 is grounded to form a voltage division circuit a, and the voltage divided at the two ends of the second resistor R2 is input into the voltage boosting circuit as a grid voltage detection value.
Furthermore, the input end of the voltage boost circuit is connected with the output end of the grid voltage detection circuit, and comprises a third resistor R3, an operational amplifier a1, a fifth resistor R5, a sixth resistor R6, a fourth resistor R4 and a first capacitor C1, an external power supply is input into the positive input end of the operational amplifier a1 after passing through the third resistor R3, one end of the fifth resistor R5 is grounded, the other end of the fifth resistor R5 is connected with the sixth resistor R6, the sixth resistor R6 is connected in parallel between the negative input end and the output end of the operational amplifier a1, the fifth resistor and the sixth resistor divide the voltage of the output end of the operational amplifier a1, the voltage divided by the fifth resistor R5 is input into the negative input end of the operational amplifier a1, the fourth resistor R4 is connected in series with the output end of the operational amplifier a1, and then is grounded through the first capacitor C1, therefore, a voltage boosting circuit is formed, and the grid voltage detection value is boosted and then sent to a first analog-to-digital conversion module in the DSP program unit.
Furthermore, the input end of the output voltage detection circuit is connected with the output end of the power circuit, and includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, an RC filter resistor R10 and an RC filter capacitor C2, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 with a larger resistance value are connected in series to form a voltage divider circuit b, the voltage divided at two ends of the ninth resistor R9 is used as an output voltage sampling value, one end of the RC filter resistor R10 is connected with the ninth resistor R9, the other end of the RC filter resistor R10 is grounded after passing through the RC filter capacitor C2 to form an RC filter circuit, and the output voltage sampling value is filtered and then sent to a second analog-to-digital conversion module in the DSP program unit.
Further, the resistance values of the seventh resistor R7 and the eighth resistor R8 are both greater than the resistance value of the ninth resistor R9.
Further, the DSP program unit includes fifteen digital modules, which are respectively: a first analog-to-digital conversion module PB1, a second analog-to-digital conversion module PB2, a third analog-to-digital conversion module PB3, a phase-locked loop module PB4, a reference sine wave generation module BP5, a switching frequency waveform generation module PB6, a sawtooth carrier generation module PB7, a duty cycle correction module PB8, a voltage error amplification module PB10, a fundamental wave filter module PB11, a third harmonic filter module PB12, a fifth harmonic filter module PB13, a multiplier module PB14, a clipping module PB15, and a comparison modulation module PB9, wherein:
the input end of the first analog-to-digital conversion module is connected with the output end of the power grid voltage detection circuit, and a power grid voltage detection value (analog quantity) is converted into a digital quantity and then sent into the phase-locked loop module;
the input end of the phase-locked loop module is connected with the output end of the first analog-to-digital conversion module, the phase of the power grid voltage is fixed, the influence caused by the phase drift of the power grid voltage is eliminated, and then the instantaneous phase of the power grid voltage is sent to the reference sine wave generation module;
the input end of the reference sine wave generation module is connected with the output end of the phase-locked loop module, receives the transmitted power grid voltage phase parameter, generates a reference sine wave for modulating the switching frequency by combining an internally set frequency fixed value parameter, and respectively sends the reference sine wave to the switching frequency waveform generation module and the duty ratio correction module;
the input end of the switching frequency waveform generating module is connected with the output end of the reference sine wave generating module, appropriate waveform transformation is carried out on the basis of the reference sine wave to generate a switching frequency waveform, and the switching frequency waveform is sent to the sawtooth carrier wave generating module;
the input end of the sawtooth carrier generation module is connected with the output end of the switching frequency waveform generation module, and according to the input switching frequency waveform, unit amplitude sawtooth carriers of corresponding periods are generated and sent to the first input end of the comparison modulation module;
the input end of the duty ratio correction module is connected with the output end of the reference sine wave generation module, and the input switching frequency function is subjected to squaring operation to obtain a corresponding duty ratio correction coefficient which is sent to the first input end of the multiplier module;
the input end of the second analog-to-digital conversion module is connected with the output end of the output voltage detection circuit, and an output voltage sampling value (analog quantity) of the power circuit is converted into a digital quantity and then sent to the first input end of the voltage error amplification module;
the input end of the third analog-to-digital conversion module gives a reference voltage, converts a reference voltage value (analog quantity) into a digital quantity, and then sends the digital quantity to the second input end of the voltage error amplification module;
the first input end of the voltage error amplification module is connected with the output end of the second analog-to-digital conversion module, the second input end of the voltage error amplification module is connected with the output end of the third analog-to-digital conversion module, the difference value of the output voltage detection value and the reference voltage is amplified, and then the amplified output voltage is sent to the fundamental wave filtering module for filtering;
the input end of the fundamental wave filtering module is connected with the output end of the voltage error amplifying module, so that a double fundamental wave component in a voltage error signal is filtered, and then the voltage error signal is sent to the third harmonic wave filtering module for further filtering;
the input end of the third harmonic filtering module is connected with the output end of the fundamental wave filtering module, and is used for filtering out a second harmonic component in the voltage error signal and then sending the voltage error signal to the fifth harmonic filtering module for further filtering;
the input end of the fifth harmonic filtering module is connected with the output end of the third harmonic filtering module, double fifth harmonic components in the voltage error signal are filtered, the filtered voltage difference signal is converted into a corresponding duty ratio, and then the duty ratio is sent to the multiplier module;
the first input end of the multiplier module is connected with the output end of the duty ratio correction module, the second input end of the multiplier module is connected with the output end of the fifth harmonic filtering module, the input duty ratio is multiplied by the duty ratio correction coefficient, certain correction is carried out on the input original duty ratio, and then the corrected duty ratio is sent to the amplitude limiting module;
the input end of the amplitude limiting module is connected with the output end of the multiplier module, amplitude limiting processing is carried out on the corrected duty ratio, the condition that the duty ratio is larger than or equal to the unit amplitude caused by system errors or other non-ideal factors is prevented, the power circuit is prevented from being damaged, and the amplitude-limited duty ratio is input into the second input end of the comparison and modulation module;
the first input end of the comparison modulation module is connected with the output end of the sawtooth carrier generation module, the second input end of the comparison modulation module is connected with the output end of the amplitude limiting module, the input constant-amplitude variable-frequency sawtooth carrier is compared with the waveform of the instantaneous duty ratio, and PWM driving pulses with modulated periods and duty ratios are generated;
and the output end of the DSP program unit is connected with a gate pole of a power switch in the power circuit.
In FIG. 1, uaRepresenting the grid voltage; u'aRepresenting the boosted grid voltage signal; u'aRepresenting the power grid voltage signal after analog-to-digital conversion; phi represents the phase of the power grid voltage reference signal obtained by a phase-locked loop PLL; omegaiAn angular frequency representing the grid voltage; t represents time; i.e. ic＝(1-k1)-k1 sin(ωit) represents a function of the variation of the available carrier frequency, where k1Representing the coefficient, and the value range is 0-0.2; i.e. ic＝1-k1|sin(ωit) | represents another function of the available carrier frequency variation; u. ofoRepresents a dc output voltage; u'oRepresents a direct current output voltage signal; u'oRepresenting the DC output voltage signal after analog-to-digital conversion; u shaperefRepresents a dc output voltage reference; u'refRepresenting the DC output voltage reference after analog-to-digital conversion; u. ofc1The control quantity generated by amplifying the voltage error is shown; f1(s) represents a second order filter transfer function adopted by the double fundamental frequency notch module; f3(s) represents a second order filter transfer function employed by a double 3 harmonic notch module; f5(s) represents a second order filter transfer function employed by a double 5 th harmonic notch module; k is a radical ofmAnd represents the output of the duty cycle correction factor, wherein,oric1Function representing the variation of an available carrier frequency, ic2A function representing a variation of another available carrier frequency; d1Represents an intermediate duty cycle; d2Represents an intermediate duty cycle; d represents the resulting available duty cycle; u. ofc2Represents a control quantity of the output of the multiplier module, wherein icFunction representing the variation of the available carrier frequency uc2Representing the control quantity generated by the multiplier module;where s denotes a complex parameter, s ═ j ω, and Q denotes a quality factor in the resonant network;wherein, represents multiplication number and multiplication;g(s) represents a symbol of a transfer function, wherein,s represents a complex parameter, S ═ j ω; c represents a filter capacitance in g(s), where C ═ 25 μ F; u shapecRepresents a voltage control amount, wherein Uc＝1V；fsIndicating a variable switching frequency at which, among other things,icindicating the function that produces the carrier frequency variation.
In FIG. 2, iaRepresenting the grid current; i.e. ic0Represents the current of the capacitor C0; i'aRepresenting the filtered inductor current; i.e. iL1Represents the inductor L1 current; i.e. iL2Represents the inductor L2 current; i.e. iD1Represents diode D1 current; i.e. iD5Represents diode D5 current; i.e. iD15Represents the current synthesized by the diodes D1 and D5;iD9represents diode D9 current; i.e. ioRepresents the output current; i.e. iE1Representing the electrolytic capacitor E1 current.
In this example: the alternating current input voltage is wide in range, 85 VAC-264 VAC, power frequency, rated input voltage 220VAC, rated output direct current voltage average value is 50-500VDC, and ripple voltage peak value is within 10V.
The parameters of each element can be selected as follows:
switching frequency: 40 kHz-100 kHz;
ac filter inductance L0: 1mH, plug-in;
ac filter capacitance C0: 275V, 2.2 μ F, plug-in;
reverse fast recovery diodes D1-D9: 600V, 35A/100 ℃;
leg inductance (L1, L2): 0.025 mH;
power devices (S1-S3): 600V, 50A/100 ℃;
electrolytic capacitor E1: 4X 680 mu F, two parallel strings and two parallel strings, 400V;
voltage transformer TR 1: the transformation ratio is 100: 1;
sampling resistance R1: 40k omega; r2: 1k omega;
control circuit operational amplifier a 1: TLC 2272;
resistance R3: 16.5k Ω;
R4：1kΩ；
R5：2kΩ；
R6：12kΩ；
grounded capacitance C1:1 nF;
voltage-dividing resistors (R7, R8): 30k omega; r9: 1k omega;
filter resistance R10: 1k omega;
filter capacitance C2: 1 nF;
power supply VDD: 3.3V direct current;
reference voltage Uref: 5.0V direct current;
a digital signal processor: and the TMS320F28377 supporting floating point operation is selected for the control module.
The embodiment provides a single-phase AC-DC conversion circuit for modulating the frequency and the width of a network current pure sine drive pulse, a corrected duty ratio and a modulated switching frequency are obtained through a control circuit to form a PWM drive pulse, and the switching states of three power switches in a power circuit are controlled, so that when the voltage of a power network is distorted, the input current always keeps a sine waveform, and current inner loop control is not needed. The embodiment realizes single-phase AC-DC conversion that the input current always keeps sine when the voltage of the power grid is distorted, the inductor works in a DCM mode, the inductance is low, the control is simple, the response is quick, and the electric energy quality pollution is prevented, so that the method is widely applied to the application occasions of vehicle-mounted or vehicle wired or wireless chargers, variable frequency air conditioners and the like.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (7)
1. The utility model provides a net flows pure sinusoidal drive pulse frequency modulation width modulation's single-phase AC-DC converting circuit which characterized in that, includes power circuit and control circuit, wherein:
the power circuit is used for completing power conversion of single-phase AC-DC;
the control circuit comprises a power grid voltage detection circuit, a voltage boosting circuit, an output voltage detection circuit and a DSP program unit; wherein:
the power grid voltage detection circuit is used for inputting the voltage obtained by dividing the power grid voltage after passing through the voltage transformer and the voltage division circuit a into the voltage boost circuit as a power grid voltage detection value;
the voltage boosting circuit is used for boosting an input power grid voltage detection value and sending the power grid voltage detection value to the DSP program unit;
the output voltage detection circuit is used for taking the voltage obtained by dividing the output voltage through the voltage division circuit b as an output voltage sampling value, filtering the output voltage sampling value through the RC filter circuit and sending the filtered output voltage sampling value to the DSP program unit;
the DSP program unit is used for processing the amplified signal of the input power grid voltage detection value and the output voltage sampling value to obtain a corrected duty ratio and a modulated switching frequency, so as to form a PWM driving pulse and control the PWM switching state of a power switch in the power circuit;
the power circuit comprises a filter circuit and a rectifying circuit, wherein:
the filter circuit mainly comprises an LC filter inductor and an LC filter capacitor, wherein one end of the LC filter inductor is connected with a live wire of a power grid, and the other end of the LC filter inductor is connected with a zero line of the power grid after passing through the LC filter capacitor to form the LC filter circuit;
the rectifying circuit comprises a single-phase rectifying bridge, a ninth diode and an electrolytic capacitor; the single-phase rectifier bridge mainly comprises first to eighth diodes, first to third power switches, a first inductor and a second inductor, wherein a first bridge arm of the single-phase rectifier bridge comprises first to fourth diodes, a first power switch and a first inductor, the second diode, the third diode, the first power switch and the first inductor form a loop in the bridge arm, the first diode is positioned at the high end of the first bridge arm, and the fourth diode is positioned at the low end of the first bridge arm; the second bridge arm of the single-phase rectifier bridge comprises fifth to eighth diodes, a second power switch and a second inductor, wherein a sixth diode, a seventh diode, the second power switch and the second inductor form a loop in the bridge arm, the fifth diode is positioned at the high end of the second bridge arm, and the eighth diode is positioned at the low end of the second bridge arm; a third bridge arm of the single-phase rectifier bridge is composed of a third power switch; the high ends of the first bridge arm and the second bridge arm are connected with the common cathode and form an output voltage anode after passing through a ninth diode; the low ends of the first bridge arm and the second bridge arm are connected in a common anode mode, and an output voltage cathode is formed; the middle points of the first bridge arm and the second bridge arm are respectively connected with two ends of the LC filter capacitor; an electrolytic capacitor is connected in parallel between the positive pole of the output voltage and the negative pole of the output voltage.
2. The grid-current pure sinusoidal driving pulse frequency-width modulation single-phase AC-DC conversion circuit according to claim 1, wherein an input terminal of the grid voltage detection circuit is connected with an input terminal of a power circuit, an output terminal of the grid voltage detection circuit is connected with an input terminal of a voltage boosting circuit, an output terminal of the voltage boosting circuit is connected with a DSP program unit, an input terminal of the output voltage detection circuit is connected with an output terminal of the power circuit, and an output terminal of the output voltage detection circuit is connected with the DSP program unit.
3. The grid current pure sine drive pulse frequency modulation and width modulation single-phase AC-DC conversion circuit according to claim 1 or 2, wherein the grid voltage detection circuit comprises a voltage transformer, a first resistor and a second resistor, the grid voltage is input into the grid voltage detection circuit after passing through the voltage transformer, the first resistor and the second resistor are connected in series and then connected in parallel to the secondary side of the voltage transformer, one end of the second resistor is grounded to form a voltage division circuit a, and the voltage divided by the two ends of the second resistor is input into the voltage boosting circuit as the grid voltage detection value.
4. The net flow pure sine drive pulse frequency modulation wide single-phase AC-DC conversion circuit according to claim 1 or 2, the voltage boosting circuit is characterized by comprising a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, an operational amplifier and a first capacitor, an external power supply is input into a positive phase input end of the operational amplifier through the third resistor, one end of the fifth resistor is grounded, the other end of the fifth resistor is connected with the sixth resistor, the sixth resistor is connected between a negative phase input end and an output end of the operational amplifier in parallel, the fifth resistor and the sixth resistor have a voltage division effect on the voltage of the output end of the operational amplifier, the voltage divided by the fifth resistor is input into the negative phase input end of the operational amplifier, the fourth resistor is connected to the output end of the operational amplifier in series and then is grounded through the first capacitor, and a power grid voltage detection value is boosted and then sent into the DSP program unit.
5. The single-phase AC-DC conversion circuit with the function of frequency modulation and width modulation of the net flow pure sine drive pulse according to claim 1 or 2, wherein the output voltage detection circuit comprises a seventh resistor, an eighth resistor, a ninth resistor, an RC filter resistor and an RC filter capacitor, the seventh resistor, the eighth resistor and the ninth resistor are connected in series to form a voltage division circuit b, the voltage divided at two ends of the ninth resistor is used as an output voltage sampling value, one end of the RC filter resistor is connected with the ninth resistor, the other end of the RC filter resistor is grounded after passing through the RC filter capacitor to form the RC filter circuit, and the output voltage sampling value is sent to the DSP program unit after being filtered.
6. The net flow pure sine drive pulse frequency modulation wide single-phase AC-DC conversion circuit according to claim 5, wherein the resistance values of the seventh resistor and the eighth resistor are both larger than the resistance value of the ninth resistor.
7. The net flow pure sine drive pulse frequency modulation width modulation single-phase AC-DC conversion circuit according to claim 1 or 2, wherein the DSP program unit comprises fifteen digital modules, which are respectively: the device comprises a first analog-to-digital conversion module, a second analog-to-digital conversion module, a third analog-to-digital conversion module, a phase-locked loop module, a reference sine wave generation module, a switching frequency waveform generation module, a sawtooth carrier generation module, a duty ratio correction module, a voltage error amplification module, a fundamental wave filtering module, a third harmonic filtering module, a fifth harmonic filtering module, a multiplier module, an amplitude limiting module and a comparison and modulation module, wherein:
the input end of the first analog-to-digital conversion module is connected with the output end of the power grid voltage detection circuit, and the analog quantity of the power grid voltage detection value is converted into digital quantity which is then sent to the phase-locked loop module;
the input end of the phase-locked loop module is connected with the output end of the first analog-to-digital conversion module, the phase of the power grid voltage is fixed, the influence caused by the phase drift of the power grid voltage is eliminated, and then the instantaneous phase of the power grid voltage is sent to the reference sine wave generation module;
the input end of the reference sine wave generation module is connected with the output end of the phase-locked loop module, receives the transmitted power grid voltage phase parameter, generates a reference sine wave for modulating the switching frequency by combining an internally set frequency fixed value parameter, and respectively sends the reference sine wave to the switching frequency waveform generation module and the duty ratio correction module;
the input end of the switching frequency waveform generating module is connected with the output end of the reference sine wave generating module, appropriate waveform transformation is carried out on the basis of the reference sine wave to generate a switching frequency waveform, and the switching frequency waveform is sent to the sawtooth carrier wave generating module;
the input end of the sawtooth carrier generation module is connected with the output end of the switching frequency waveform generation module, and according to the input switching frequency waveform, unit amplitude sawtooth carriers of corresponding periods are generated and sent to the first input end of the comparison modulation module;
the input end of the duty ratio correction module is connected with the output end of the reference sine wave generation module, and the input switching frequency function is subjected to squaring operation to obtain a corresponding duty ratio correction coefficient which is sent to the first input end of the multiplier module;
the input end of the second analog-to-digital conversion module is connected with the output end of the output voltage detection circuit, and the analog quantity of the output voltage sampling value is converted into digital quantity which is then sent to the first input end of the voltage error amplification module;
the input end of the third analog-to-digital conversion module gives a reference voltage, the analog quantity of the reference voltage value is converted into a digital quantity, and the digital quantity is sent to the second input end of the voltage error amplification module;
the first input end of the voltage error amplification module is connected with the output end of the second analog-to-digital conversion module, the second input end of the voltage error amplification module is connected with the output end of the third analog-to-digital conversion module, the difference value of the output voltage detection value and the reference voltage is amplified, and then the amplified output voltage is sent to the fundamental wave filtering module for filtering;
the input end of the fundamental wave filtering module is connected with the output end of the voltage error amplifying module, so that a double fundamental wave component in a voltage error signal is filtered, and then the voltage error signal is sent to the third harmonic wave filtering module for further filtering;
the input end of the third harmonic filtering module is connected with the output end of the fundamental wave filtering module, and is used for filtering out a second harmonic component in the voltage error signal and then sending the voltage error signal to the fifth harmonic filtering module for further filtering;
the input end of the fifth harmonic filtering module is connected with the output end of the third harmonic filtering module, double fifth harmonic components in the voltage error signal are filtered, the filtered voltage difference signal is converted into a corresponding duty ratio, and then the duty ratio is sent to the multiplier module;
the first input end of the multiplier module is connected with the output end of the duty ratio correction module, the second input end of the multiplier module is connected with the output end of the fifth harmonic filtering module, the input duty ratio is multiplied by the duty ratio correction coefficient, certain correction is carried out on the input original duty ratio, and then the corrected duty ratio is sent to the amplitude limiting module;
the input end of the amplitude limiting module is connected with the output end of the multiplier module, amplitude limiting processing is carried out on the corrected duty ratio, and then the amplitude-limited duty ratio is input into the second input end of the comparison modulation module;
the first input end of the comparison modulation module is connected with the output end of the sawtooth carrier generation module, the second input end of the comparison modulation module is connected with the output end of the amplitude limiting module, the input constant-amplitude variable-frequency sawtooth carrier is compared with the waveform of the instantaneous duty ratio, and PWM driving pulses with modulated periods and duty ratios are generated;
and the output end of the DSP program unit is connected with a gate pole of a power switch in the power circuit.
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| JPH08266059A (en) * | 1995-03-24 | 1996-10-11 | Okuma Mach Works Ltd | Power converter |
| CN102097929A (en) * | 2011-03-18 | 2011-06-15 | 上海交通大学 | Single-level power factor corrector controlled by complete open loop |
| CN103312199A (en) * | 2013-05-14 | 2013-09-18 | 上海交通大学 | Single-phase power factor corrector in direct network-side power control |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08266059A (en) * | 1995-03-24 | 1996-10-11 | Okuma Mach Works Ltd | Power converter |
| CN102097929A (en) * | 2011-03-18 | 2011-06-15 | 上海交通大学 | Single-level power factor corrector controlled by complete open loop |
| CN103312199A (en) * | 2013-05-14 | 2013-09-18 | 上海交通大学 | Single-phase power factor corrector in direct network-side power control |
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| 单相电压源整流器直接储能控制的研究;李新颜等;《电气自动化》;20151231;第37卷(第3期);全文 * |
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